This invention deals generally with boats and more specifically with a boat upon which is mounted an elevator device to raise personnel above the boat deck.
Most of us are vaguely aware that highway bridges must be inspected regularly, but few are aware of the procedures involved in such inspections. Since inspection of the underside of such structures is federally mandated, there must be some way to gain access to the structure below the roadway. Most bridge inspections are performed by walking on the ground, from ladders, with conventional bucket trucks, or, for bridges high above rivers, by using articulating cranes with platforms or buckets on them.
The cranes almost always require lane closures on the bridge, although occasionally a shoulder closure will suffice, and often bridges that have been load rated cannot be accessed by cranes because the cranes are too heavy. For such bridges catenary cables with sliding or rolling scaffolds are an alternative. Catenary cables do not generally require lane closures, but their installation is difficult, and often dangerous, work.
There is an alternative for bridges which are not too high above the ground level they cross. That alternative is to use an aerial boom with a bucket and to support it from a vehicle that can traverse the ground below the bridge. One such apparatus is an aerial boom mounted upon a four wheel drive truck, such as a Hummer. Such vehicles are presently being used for some bridge inspections. The limitation of such vehicles is that they can not operate in or cross rivers of any significant depth. In fact, the depth limit is determined by the height of the vehicle engine above the bottom of the wheels, and that is typically only about 2xc2xd feet.
Some use has been made of boats for access to the underside of bridges, but they are makeshift arrangements which are time consuming to set up and limited in height. Typically, they have simply involved conventional scaffolds erected aboard a boat and extending above deck height. Operation of such boat and scaffold systems in tidal areas often requires multiple changes and adjustments in the scaffolding heights during the course of the bridge inspection. Clearly, such scaffolds must be completely disassembled before the boat is moved over a road to a new location.
It would be very beneficial to have available a variable lift device that has the capability of inspecting or maintaining different height bridges above deep water without any use of the bridge roadway itself and without time consuming set up of scaffolds. The versatility of such a unit would be enhanced even further if it could be moved over roads without being disassembled.
The present invention is an outboard motor propelled catamaran boat with a permanently attached centered elevator lift that can raise personnel as high as 32 feet above the waterline. Although the preferred embodiment of the boat itself is narrow enough to be transported over roads on a trailer, partially water-filled outrigger pontoons increase the beam to a width sufficient to stabilize the boat when the lift is fully raised. The outrigger pontoons are mounted on pivoting arms so that they can be pivoted back aboard the boat for transport, and when the outrigger pontoons are aboard and resting on their supports above the deck, they are well below the height of the lowered elevator lift. The typical road height of the boat on its trailer is therefore only 13 feet.
The preferred embodiment of the invention uses two outrigger pontoons extending off only one side of the boat. This configuration yields a valuable benefit for bridge maintenance. It permits one side of the boat to be moved close up against bridge supports, and since the personnel platform atop the elevator lift is essentially the same width as the boat, personnel can easily inspect or work on the bridge support to which they are adjacent.
The invention therefore furnishes simple access to bridges above deep water, but is easily transported to locations where bridge work is required. Furthermore, the relatively small size of the boat permits it to be launched at conventional boat ramps after which it can move under its own power to the bridge location.